CS5166GDWR16 View Datasheet(PDF) - ON Semiconductor
Part Name
Description
MFG CO.
'CS5166GDWR16' PDF : 25 Pages View PDF
CS5166
reaching the output voltage specification limits. When load
current suddenly increases from its minimum level, the
output capacitor is pre−positioned +25 mV. Conversely,
when load current suddenly decreases from its maximum
level, the output capacitor is pre−positioned −25 mV (see
Figures 16, 17, and 18). For best Transient Response, a
combination of a number of high frequency and bulk output
capacitors are usually used.
If the Maximum On−Time is exceeded while responding
to a sudden increase in Load current, a normal off−time
occurs to prevent saturation of the output inductor.
Trace 3− Load Current (5.0 A/10 mV/div.)
Trace 4− VOUT (100 mV/div.)
Figure 16. Output Voltage Transient Response to
a 14 A Load Pulse, VOUT = +2.825 V (DAC = 10111)
Trace 1− GATE(H) (10 V/div.)
Trace 2− Inductor Switching Node (5.0 V/div.)
Trace 3− Load Current (5.0 A/div)
Trace 4− VOUT (100 mV/div.)
Figure 17. Output Voltage Transient Response to a
14 A Load Step, VOUT = +2.825 V (DAC = 10111)
Trace 1− GATE(H) (10 V/div.)
Trace 2− Inductor Switching Node (5.0 V/div.)
Trace 3− Load Current (5.0 A/div)
Trace 4− VOUT (100 mV/div.)
Figure 18. Output Voltage Transient Response to a
14 A Load Turn−Off, VOUT = +2.825 V (DAC = 10111)
Power Supply Sequencing
The CS5166 offers inherent protection from undefined
start up conditions, regardless of the 12 V and 5.0 V supply
power up sequencing. The turn on slew rates of the 12 V and
5.0 V power supplies can be varied over wide ranges without
affecting the output voltage or causing detrimental effects to
the buck regulator.
PROTECTION AND MONITORING FEATURES
Overcurrent Protection
A loss−less hiccup mode current limit protection feature
is provided, requiring only the Soft Start capacitor to
implement. The CS5166 provides overcurrent protection by
sensing the current through a “Droop” resistor, using an
internal current sense comparator. The comparator
compares this voltage drop to an internal reference voltage
of 76 mV (typical).
If the voltage drop across the “Droop” resistor exceeds
this threshold, the current sense comparator allows the fault
latch to be set. This causes the regulator to stop switching.
During this overcurrent condition, the CS5166 stays off for
the time it takes the Soft Start capacitor to slowly discharge
by a 2.0 μA current source until it reaches its lower 0.7 V
threshold.
At that time the regulator attempts to restart normally by
delivering short gate pulses to both FET’s. The CS5166 will
operate initially in its extended off time mode with a 50%
duty cycle, while the Soft Start capacitor is charged with a
60 mA charge current. The gates will switch on while the
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